finish the documentation

this is an attempt at finishing the documentation for real.

the convention is

• start sentences with capital letter, speaks as 3rd person and end with period
• specify non-trivial cases and returns in the doc, otherwise, leave that to the tests
• use mathematical formulae to make things more clear

💡 Note

might supersede !184

For now, i completely skipped FRI because i thought we could do that in a later MR, as it was added later and is not even part of a public release yet.

I also went a bit faster on aPlonK as it is so complex and we will likely never use it.

changelog

• moves the RUSTDOCFLAGS for Katex activation to .cargo/config.toml
• adds simple_mermaid for Mermaid graphs
• upgrades Katex from 0.10.0 to 0.16.21 for matrix support
• documentation
  • algebra: check the length for algebra::powers_of
  • algebra::linalg: use exact matches in the error tests and use struct errors
  • error: change some errors to struct errors
  • fs: rename some arguments, e.g. block_hashes to hashes and dump_dir to directory
  • zk: inline check_degree_is_too_large
  • fec
  • semi_avid
  • kzg
  • aplonk
  • fri
  • Komodo